1. Field of the Invention
The present invention relates to an electrically conductive damper device for a speaker, which can be advantageously used in such a speaker as having a large amplitude.
2. Description of the Related Art
In the production of the speaker, an electrically conductive member for inputting voice signals into a voice coil has been integrally attached to a damper in many cases, for the purpose of decreasing number of wiring works. For this purpose, the damper has been composed of damper material such as a fabric or non-woven fabric provided with corrugations, and the electrically conductive member which is formed of braided metallic wires according to a shape of the corrugations and incorporated into the damper material by sewing with fibers such as threads.
However, the above described damper has had poor applicability, because when it has been assembled into the speaker having the large amplitude, a neck portion of the damper and its surrounding area may be locally bent, resulting in break-downs of the damper material and the braided metallic wires.
The present invention has been made in view of the above described circumstances, and it is an object of the invention to provide an electrically conductive damper device for a speaker in which an additional reinforcing damper is attached to a main damper in order to reinforce a neck portion of the electrically conductive damper, and these two sheets of dampers are bonded to each other by means of resin, whereby a local bending is reduced, and break-downs of the damper material and the braided metallic wires can be prevented.
It is also an object of the invention to provide an electrically conductive damper device for a speaker in which properties of the damper can be adjusted by varying an outer diameter of the reinforcing damper or selecting the resin as an adhesive.
In order to solve the above described problems, there is provided according to the invention, an electrically conductive damper device for a speaker comprising a main damper which is formed of damper material having metallic wires attached thereto, and a reinforcing damper which is attached to a part of the main damper on which a voice coil bobbin is mounted.
According to the above described structure, an additional sheet of the damper material is attached to the main damper for the purpose of reinforcing a neck portion of the electrically conductive damper, and break-downs of the damper material and the metallic wires incorporated therein can be prevented.
In the electrically conductive damper device for the speaker according to another aspect of the invention, the damper material is formed of a fabric impregnated with thermosetting resin, and the metallic wires are formed of electrically conductive material, the main damper being formed by attaching the metallic wires to the fabric by sewing.
This will moderate a local bending of the damper and can prevent break-downs of the damper material and the metallic wires incorporated therein.
In the electrically conductive damper device for the speaker according to a further aspect of the invention, the reinforcing damper is attached to such an area of the main damper that a local bending occurring at the mounting part of the voice coil bobbin when the voice coil bobbin is driven by a voice coil may be reduced, whereby the material of the main damper and the metallic wires may be prevented from breaking down.
According to this structure, in the area of the main damper provided with the reinforcing damper, a local bending will be reduced. Because the outer peripheral area will be adequately bent on the other hand, the local bending will be moderated, and the break-downs of the damper material and the metallic wires which have been incorporated will be prevented.
In the electrically conductive damper device for the speaker according to still another aspect of the invention, the main damper and the reinforcing damper are bonded to each other by means of an adhesive.
By selecting the resin to be employed for bonding, properties of the damper can be adjusted and the break-downs of the damper material and the metallic wires which have been incorporated will be prevented.
In the electrically conductive damper device for the speaker according to a still further aspect of the invention, the adhesive has an inner loss to such an extent that sympathetic vibrations of the electrically conductive damper occurring when the voice coil bobbin is driven may be dampened.
By thus selecting the resin having the large inner loss as the adhesive, an anti-vibration effect of dampening sympathetic vibrations of the damper caused by the metallic wires which have been incorporated can be attained.
In the electrically conductive damper device for the speaker according to a still further aspect of the invention, the main damper and the reinforcing damper are bonded to each other by applying the adhesive.
By selecting the resin to be employed for bonding, the properties of the damper can be adjusted and the break-downs of the damper material and the metallic wires which have been incorporated will be prevented.
In the electrically conductive damper device for the speaker according to a still further aspect of the invention, the main damper and the reinforcing damper are bonded to each other by sandwiching the adhesive between them and by fusion bonding.
This enables the break-downs of the damper material and the metallic wires incorporated therein to be prevented.